Mr. Obama spoke just after noon to a sea of cheering people, appearing to number well over a million, who packed the National Mall from the Capitol to the Washington Monument and beyond. Four hours later, at the end of the parade route, he left his car and strolled with his wife along Pennsylvania Avenue on the final steps of a long march to the White House, holding hands and waving to cheering crowds.

In his inaugural address, Mr. Obama acknowledged the change his presidency represented, describing himself in his inaugural address as a “man whose father less than sixty years ago might not have been served at a local restaurant.” But although the crowd and the podium around him were full of elated African Americans, Mr. Obama, the first black to become president, did not dwell on that in his speech.